1. Field
This disclosure relates generally to compounds, pharmaceutical compositions and methods of use of the compounds and compositions containing them. This disclosure relates more particularly to certain carboxamide compounds and pharmaceutical compositions thereof, and to methods of treating and ameliorating disorders and conditions related to oxidative stress, mitochondrial dysfunction, free radical damage and metabolic inefficiency, among others.
2. Technical Background
Adiponectin is a protein hormone exclusively expressed in and secreted from adipose tissue and is the most abundant adipose-specific protein. Adiponectin has been implicated in the modulation of glucose and lipid metabolism in insulin-sensitive tissues. Decreased circulating adiponectin levels have been demonstrated in some insulin-resistant states, such as obesity and type 2 diabetes mellitus and also in patients with coronary artery disease, atherosclerosis and hypertension. Adiponectin levels are positively correlated with insulin sensitivity, HDL (high density lipoprotein) levels and insulin stimulated glucose disposal and inversely correlated with adiposity and glucose, insulin and triglyceride levels. Thiazolidinedione drugs, which enhance insulin sensitivity through activation of the peroxisome proliferator-activated receptor-γ, increase endogenous adiponectin production in humans.
Adiponectin binds its receptors in liver and skeletal muscle and thereby activates the 5″-AMP-activated protein kinase (AMPK) pathway. Adiponectin receptors 1 and 2 are membrane-bound proteins found in skeletal muscle and liver tissue. Being a multi-substrate enzyme, AMPK regulates a variety of metabolic processes, such as glucose transport, glycolysis and lipid metabolism. It acts as a sensor of cellular energy homeostasis and is activated in response to certain hormones and muscle contraction as well as to intracellular metabolic stress signals such as exercise, ischemia, hypoxia and nutrient deprivation. Once activated, AMPK switches on catabolic pathways (such as fatty acid oxidation and glycolysis) and switches off ATP-consuming pathways (such as lipogenesis). Adiponectin improves insulin sensitivity by directly stimulating glucose uptake in adipocytes and muscle and by increasing fatty acid oxidation in liver and muscle, resulting in reduced circulating fatty acid levels and reduced intracellular triglyceride contents. Moreover, adiponectin decreases glycogen concentration by reducing the activity of glycogen synthase. Adiponectin also plays a protective role against inflammation and atherosclerosis. It suppresses the expression of adhesion molecules in vascular endothelial cells and cytokine production from macrophages, thus inhibiting the inflammatory processes that occur during the early phases of atherosclerosis.